Aortocaval fistula is a rare and devastating complication of abdominal aortic aneurysm (AAA), in which the aneurysm erodes into the inferior vena cava.
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Epidemiology
Spontaneous rupture of an abdominal aortic aneurysm into the adjacent inferior vena cava occurs in <1% of all aneurysms and in ~3% of ruptured aortic aneurysms 1.
Clinical presentation
The features can be very atypical leading to a delay in diagnosis. The various factors that influence the clinical presentations are the origin, size, location and duration of the fistula:
- backache
- high output cardiac failure
- bilateral pedal edema (venous hypertension in the lower half of body)
- hepatic failure
- renal insufficiency (reduced renal blood flow)
- hematuria
- continuous bruit in the abdomen 4
Radiographic features
Aortography is the modality of choice. Color Doppler ultrasound, CT and MRI may also demonstrate the same non-invasively. At times, the presence of a mural thrombus may obstruct the fistula.
Treatment and prognosis
Urgent surgical exploration and repair. Operative mortality of spontaneous aortocaval fistula is about 20 to 55%, figures being high predominantly due to delayed diagnosis or misdiagnosis.
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